Shapes

// Compiled after a small session between Martin Breidt & Mads Drøschler Based on a WebGL function.
// 14.10.2018
// License: https://creativecommons.org/licenses/by-nc-sa/3.0/
// Modified : 03.22.2021 by Saul Espinosa For Redshift 3d
float lPolygon(vector p, int n)
{
    float a = atan2(p[0], p[1]) + M_PI;
    float r = 2*M_PI/float(n);
    return cos(floor(0.5 + a/r) * r - a) * length(p);
}
shader Shapes
[[  string help = "Generates Procedural Shapes",
    string label = "Shapes" ]]
(
    point Po = point(u, v, 0),
    int nSides = 3
        [[ string help = "Number of polygon sides",
        string label = "UVW",
        int max = 25,
        int min = 3 
        ]],  
    float Softness = 0.09
        [[ 
        float min = 0.0,
        float max = 2.0
        ]],  
    float Radius = 0.4
        [[ 
        float min = 0.001, 
        float max = 1 
        ]],  
    float Stretch_U = 1.0
        [[
        float min = 0,
        float max = 2
        ]],
    float Stretch_V = 1.0
        [[
        float min = 0,
        float max = 2
        ]],
    float Star_Effect = 1.0
        [[ string help = "A value > 0 will cause the shape to become more star-like along the W coordinate",
        float min = 0,
        float max = 2
        ]],
    vector Offset = 0.0
        [[ string help = "Translation of pattern. Use a Z value > 0 to move towards a star-like pattern" ]],
    color Color_Shape = color(1),
    color Color_Background = color(0),
    output color Out = 0,
)
{
    vector p = abs(Po-floor(Po));        
    p = p - vector(0.5, 0.5, 0);
    p = (p - Offset) *  vector(Stretch_U, Stretch_V, Star_Effect )/ Radius;
    float d = lPolygon(p, int(mod(nSides-3, 60.)+3.));
    Out = color(smoothstep(Radius, Radius+Softness, d)); 
    Out = (1-Out)*Color_Shape+(Out*Color_Background);  // added colors for shape and background //Mads
}